The present invention relates to new derivatives of non-steroidal anti-inflammatory, analgesic and/or antipyretic substances, to processes for their production and to novel pharmaceutical compositions and dosage forms containing them.
More specifically, the present invention relates to the therapeutic use of new salts of non-steroidal anti-inflammatory analgesic and/or antipyretic substances that are useful in the treatment of superficial or deep inflammatory conditions, such as erythemas of various origins, inflammation of the joints or inflammation of bacterial origin. In the present specification, the abbreviation "NSA" will be used to denote the expression "non-steroidal anti-inflammatory, analgesic and/or antipyretic substance".
Typical NSAs in widespread use include acetylsalicylic acid (aspirin), 4-(2-methylpropyl)benzenacetic acid (ibufenac), .alpha.-methy-4-(2-methylpropyl)benzenacetic acid (ibuprofen) and 1-(4-chlorobenzoyl)-5-methoxy-1H-indole-3-acetic acid (indomethacin).
However these NSAs suffer the disadvantage that when administered orally, they tend to cause irritation of the stomach, even leading to bleeding and stomach ulcers.
A further disadvantage of available NSAs is that they generally are highly hydrophilic and consequently are not readily converted into dosage forms which are adapted to partition into the lipid phase. Also available dosage forms are not readily adapted for transcutaneous administration nor for formulation into convenient sustained release forms.
In an attempt to avoid these disadvantages a class of NSAs has been developed, which contain a basic nitrogen atom or atoms, which may be present for example as primary, secondary or tertiary amino groups, or other nitrogen-containing groups, such as amido groups. Examples include 2-((2,6-dichloro-phenyl)amino)benzene-acetic acid (diclofenac) and (4-hydroxy-2-methyl-N-2-pyrydinyl-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide (piroxicam).